如何在前端的每个API调用之前设置检查条件（即用户是否登录）？

I am new to Angular JS and Django. I am working on a project in which back end is implemented using Django framework. In this project multiple API's are there. Our front end is developed using Angular JS (Actually it is Angular JS Single page Application).I want to know that what would be the way to put a check condition that user is logged in or not before each API call.Because we want to reduce unnecessary Api calling until a user logged in. Currently , However we have implemented authentication mechanism in our back end part but we also want to implement some mechanism in front end so that until a user logged in ,no request will pass to server. I am new to Angular JS and Django. I am working